Use of the human vaccine, Mycobacterium bovis Bacillus Calmette Guerin in deer

Authors: Palmer, Mitchell; Thacker, Tyler

Submitted to: Frontiers in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2018
Publication Date: 10/8/2018
Citation: Palmer, M.V., Thacker, T.C. 2018. Use of the human vaccine, Mycobacterium bovis Bacillus Calmette Guerin in deer. Frontiers in Veterinary Science. 5:244. https://doi.org/10.3389/fvets.2018.00244.
DOI: https://doi.org/10.3389/fvets.2018.00244

Interpretive Summary: The only vaccine ever approved for human tuberculosis was developed a century ago from an isolate of the bacteria Mycobacterium bovis derived from a tuberculous cow. Initial safety and efficacy studies of a weakened version of this isolate were conducted in cattle and other animals. In 1921 the first human, an infant, was orally dosed with this attenuated strain that came to be known as M. bovis bacillus Calmette-Guerin (BCG); named for Albert Calmette and Camille Guerin, two French scientists that developed the strain. Since 1921, billions of people have been vaccinated with BCG making it the oldest, most widely used, and safest vaccine in use today. It is also the tuberculosis vaccine most studied for use in wildlife species including deer. While BCG vaccination of deer may not reliably prevent infection, it consistently decreases disease severity. It is believed that decreased disease severity will result in decreased disease transmission; however, this hypothesis remains to be proven. Safety studies in white-tailed deer show BCG may persist in tissues for up to 12 months; a factor to be considered in deer used for food. Methods of vaccine delivery to free-ranging deer are under investigation, both in the laboratory and in the field. The ideal delivery method is effective, efficient and safe. Studies on the use of BCG in deer parallel studies in other countries with wildlife reservoirs of M. bovis, specifically the European badger in Great Britain and the Republic of Ireland, the brushtail possum in New Zealand and wild boar in the Iberian Peninsula. As with deer, BCG vaccination does not absolutely prevent infection, but does decrease disease severity in badgers, possums and wild boar.

Technical Abstract: The only vaccine ever approved for human tuberculosis was developed a century ago from an isolate of Mycobacterium bovis derived from a tuberculous cow. Initial safety and efficacy studies of an attenuated version of this isolate were conducted in cattle and other animals. In 1921 the first human, an infant, was orally dosed with this attenuated strain that came to be known as M. bovis bacillus Calmette-Guerin (BCG); named for Albert Calmette and Camille Guerin, two French scientists that developed the strain. Since 1921, billions of people have been vaccinated with BCG making it the oldest, most widely used, and safest vaccine in use today. It is also the tuberculosis vaccine most studied for use in wildlife species including deer. While BCG vaccination of deer may not reliably prevent infection, it consistently decreases lesion severity, minimizing large, necrotic lesions, which often contain large numbers of bacilli. It is believed that decreased lesion severity correlates with decreased disease transmission; however, this hypothesis remains to be proven. Safety studies in white-tailed deer show BCG may persist in lymphoid tissues for up to 12 months; a factor to be considered in deer used for food. Beyond efficacy and safety, methods of vaccine delivery to free-ranging deer are under investigation, both in the laboratory and in the field. The ideal delivery method is effective, efficient and safe for non-target species, including livestock. Ingestion of BCG by cattle is of special concern as such cattle may present as “false positives” using currently approved diagnostic methods, thus interfering with efforts by animal health agencies to monitor cattle for tuberculosis. Studies on the use of BCG in deer parallel studies in other countries with wildlife reservoirs of M. bovis, specifically the European badger in Great Britain and the Republic of Ireland, the brushtail possum in New Zealand and wild boar in the Iberian Peninsula. As with deer, BCG vaccination does not absolutely prevent infection, but does decrease disease severity in badgers, possums and wild boar.